If you have ever tied to share a collection of photos with friends or family, you know what a challenge it is. You can upload them to an on-line sharing service or your own Web site, e-mail them one at a time, or put them on a CD and deliver them. All of these methods are time-consuming and filled with potential problems—especially with large, print-quality images. With peer-to-peer (P2P) photo sharing you can avoid all of these problems.

Peer-to-peer file exchange is what you are doing when you share files while instant messaging (IM) or when using Apple's Photocasting. However, there are applications specifically devoted to this task. The biggest difference between peer-to-peer exchanges and other forms of photo sharing is that P2P doesn't use a central service. Two computers are connected directly together although images may be temporarily stored on a server as they are being exchanged. Because of the different technologies in use, the concept is evolving from meaning just the narrowly defined computer to computer to include the broader idea of person to person transfers.

There are variations in the way these programs work. For example, Pando lets you browse your system for images to send and adds any you select to a list called a package. You then specify one or more e-mail addresses and click the Send button. Pando then sends an e-mail with a small file attachment to your recipients and uploads the full contents of your Package to the Pando network. When the recipient opens the e-mail and clicks a thumbnail image, the files are transferred to them simultaneously from your computer and Pando's. No one, including Pando, has access to your encrypted files except for you and your intended e-mail recipients.

Peer-to-peer photo sharing is a new field so there is quite a difference in the features that programs offer. For example, Hello protects you from viruses by automatically confirming that all JPG files are valid pictures before allowing them to be traded. Pixpo lets you broadcast video as well as share photos right from your own computer. GoToMyPc and Mionet are designed to let you access your own photos and applications from a remote computer.